Test tube

ABSTRACT

A closed-bottom test tube has a lower inner surface coated with a reagent. A slidable portion sealingly engaging the inner wall of the test tube is inserted downwardly to maintain a quantity of liquid in continuous contact with the reagent. Pressure relief means within the piston provides for the discharge of air trapped between the piston and the liquid.

United States Patent Marston 1 Feb. 11, 1975 [54] TEST TUBE 3,748,099 7/1973 Horlach 23/259 3,768,979 10 1973 M 'd 23 259 [751 lnvemo" Judm Marsmm scotlsdale' 3,802,843 4/1974 141?: 23/292 x [73] Assignee: Blood Services, Scottsdale. Ariz.

7 Primary Examiner-Morris O. Wolk May 1973 Assistant Examiner-Sidney Marantz [21] Appl, N 357,883 Attorney, Agent, or Firm-William l-l. Drummond;

Gregory J. Nelson; Don J. Flickinger [52] US. Cl. 23/259, 23/230 B,22O36//239025, [57] ABSTRACT 51 C] 30 3 4 0 1/10 GOln 33/16 A closed-bottom test tube has a lower inner surface coated with a reagent. A slidable portion sealingly en- [58] Field of Search 23/259, 292, 253 R, 230 B gaging the 1nner wall of the test tube 15 mserted down- [56] References Cited wardly to maintain a quantity of liquid in continuous UNITED STATES PATENTS contact with the reagent. Pressure relief means within 3 4 798 /1 hh 23/292 X the piston prov1des for the d1scharge of an trapped be- 1 au 3,481,477 12/1969 Farr a 23/259 x tween the the 3,615,222 10/1971 Mead 23/259 X 1 Claim, 8 Drawing Figures /4 l l l I "ll Ill/Hil l9 /9 li a I I3 2/ .T?: E: IT T: E:

ZZZTENTEU 13575 3,865 552 sum 10F 2 l4 llHlM FIE-4 I TEST TUBE This invention relates to laboratory testing apparatus.

More specifically, the invention concerns a test tube for containing and transporting a small quantity of blood serum.

In a further aspect, the invention concerns a test tube in which the blood serum is maintained in contact with a reagent coating within the bottom of the test tube to allow an interaction between the serum and the reagent during transportation.

Post-transfusion hepatitis, the manifestation of hepatitis subsequent to blood transfusion, has been for some time a common and disconcerting phenomenon. During the middle 1960s, researchers were able to identify a virus which is now commonly known as Hepatitis- Associated Antigen (HAA) or Australia antigen. Researchers implied that the presence of this antigen in blood is associated with serum hepatitis and therefore, if present in the blood of the donor, was transferred to the recipient by means of blood transfusion and responsible for post-transfusion hepatitis.

Pursuant to the identification of Hepatitis-Associated Antigen, work began on developing feasible methods for its detection. The resultant developmental work cuiminated with two procedures, agar gel diffusion and counterelectropheresis, which were licensed by the Public Health Service Department of Health, Education and Welfare as reported in the Federal Register, Vol. 37, No. 106, June 1, 1972, to become effective July 1, l972, and incorporated into Title 42, United States Code, Chapter 1, Section 73. While affording the public a measure of protection, the Public Health Service recognized that these two methods were capable of detecting only 20% -25% of the bloods implicated in causing post-transfusion hepatitis. Despite the employment of the agar gel diffusion and counterclectropheresis methods, it is estimated that at least 30,000 cases of hepatitis annually can be traced to transfused blood.

In the early 1960's the integration of radiochemical techniques offering high degrees of sensitivity and immunological techniques which provide exquisite specificity was achieved in the development of radioimmunoassay. For a comprehensive understanding of this system, refer to Radioimmunoassay", A. Seidner, Cadence, July-August, 1972. Recently, the technology of radioimmunoassay has been successfully adapted to the detection of Hepatitis-Associated Antigen. This method is approximately 100 times more sensitive than existing procedures, and it is estimated that the introduction of this technique into general use should more than double the detection of blood, serum and plasma units harboring the hepatitis infection. The Public Health Service, recognizing the superiority of this test, established standards for the use of radioimmunoassay in the detection of Hepatitis-Associated Antigen, as reported in the Federal Register, Vol. 37, No. 146. The amendment to the regulations became effective immediately upon publication.

The radioimmunoassay technique for the detection of Hepatitis-Associated Antigen in blood samples is relatively simple. A complete description thereof is found in a brochure published by the Radio Pharmaceutical Products Division, Abbot Laboratories, North Chicago, lll., wherein the methodology is referred to by the trade name Ausria-l25 Test. According to this procedure, 0.1 milliliter of blood serum or plasma is delivered to the bottom of a test tube which has previously been coated with a reagent having an affinity for Hepatitis-Associated Antigen. The test tube is shaped and sized for insertion into a radioactivity counter. It is emphasized that the serum must be delivered to the bottom of the tube and that the tube is gently tapped to break the surface tension, distributing the serum evenly over the bottom surface of the tube. The tube is then covered to prevent evaporation during a 16- hour incubation period. Again, it is emphasized that the tube must be maintained in a rack on a level surface so that the liquid covers the bottom and remains in contact with the reagent. During incubation, Hepatitis- Associated Antigen, if present, will bind to the reagent on the walls and bottom of the tube.

After incubation, the contents of the tube is aspirated and washed several times with a rinse solution, thereby leaving only the bound antigen-reagent antibody on the walls of the tube. Thereafter, 0.1 milliliter of a radioactive isotope solution, diluted iodine I25, is added to the bottom of the test tube, which is then covered to prevent evaporation and incubated for minutes at room temperature. During this abbreviated incubation, the radioactive isotope links with the previously bound antigen. After the tube is emptied and washed, as previously described, the tube is inserted into a radioactivity counter wherein the radioactivity is measured. Comparison with controls indicates whether the serum sample is HAA positive or negative.

While the radioimmunoassay system is relatively simple, yet exceedingly sensitive, it has certain inherent limitations which ultimately prevent widespread acceptance and use. The counting equipment requires a capita] investment of several thousands of dollars, which immediately restricts its use to larger testing centers, thus denying smaller communities and blood service organizations the benefit of the improved testing technology. Effective operation of the equipment requires trained personnel having a radio-isotope license, the registration granted by the Atomic Energy Commission. Further, since the first incubation period must begin shortly after receiving the blood from the donor and no suitable method heretofore has been devised for maintaining the serum in contact with the reagent during handling, the transportation or shipment of samples to a suitable testing facility is not feasible.

Obviously, as hereinbefore indicated in connection with the amendment to the rules and regulations of the Public Health Service, it would be in the best public interest if all donated blood could be subjected to radioimmunoassay for the detection of Hepatitis-Associated Antigen. It is equally apparent, in view of current shipping and transportation technology, that blood samples could be shipped considerable distances to suitable testing facilities during the 16-hour incubation period.

Accordingly, it is a primary object of the present invention to provide for the shipment of blood samples during the incubation period thereof to suitable testing facilities wherein the sample may be subjected to radioimmunoassay for the detection of Hepatitis-Associated Antigen.

Another object. of the present invention is the provision of a test tube wherein the blood serum is maintained in constant contact with a reagent coating in the bottom of the test tube during shipment.

Yet another object of the present invention is the provision of a test tube of the above type in which the serum is retarded from evaporation or spillage and is maintained in constant contact with the reagent coating irrespective of the disposition of the test tube during shipment.

Yet still another object of the present invention is the provision of a test tube in which the blood may be properly packaged for shipment by one having ordinary skills in the art and without requiring specialized trainmg.

Briefly, to accomplish the desired objectives of the present invention in accordance with a preferred embodiment thereof, first provided is an elongate hollow test tube closed on the bottom end, which test tube is sized and shaped to be inserted into a radioactivity counter. The inner surface of the bottom of the test tube is coated with a reagent in accordance with the test function to be performed. A piston member extending transversely across the test tube and sealingly peripherally engaging the inner wall of the test tube is dimensioned to be slidably received downward therein. After the sample serum has been inserted into the test tube, a handle member extending upwardly from the piston is used to insert the piston downwardly into the test tube to rest upon the upper surface of a liquid sample to maintain the liquid in constant contact with the reagent irrespective of the subsequent disposition of the test tube. A pressure relief aperture in the piston, sized to be sensitive to the viscosity differential between the liquid sample and air permits the discharge of air therethrough from within the test tube as the piston is urged downwardly by the operating handle. Continued downward movement of the piston ultimately spaces the piston above the bottom of the test tube at a distance corresponding to the height of the column of serum therein. The cavity created by the space between the bottom of the test tube and the piston thus evacuated of air assumes a volume equal to the volume of the liquid serum contained therein, assuring that the serum will be maintained in constant contact with the reagent coating.

The objects and advantages of the present invention will become more readily apparent to those skilled in the art from the following detailed description thereof taken in conjunction with the drawings, in which:

FIG. 1 is an elevation view in section of a test tube constructed in accordance with the teachings of the present invention;

FIG. 2 is a partial sectional view of the lower portion of the test tube of the present invention, specifically chosen to illustrate the reagent coating therein;

FIG. 3 is a view corresponding to the illustration of FIG. 2 and specifically showing the preferred method of introducing the serum sample into the bottom of the tube;

FIG. 4 is a view corresponding to the view of FIG. 3 and especially detailing the relationship between the reagent coating and the deposited serum sample;

FIG. 5 is a perspective view of an alternately preferred embodiment of the present invention;

FIG. 6 is a sectional view taken along the line 66 of FIG. 5;

FIG. 7 is a partial elevational view, partly in section, illustrating yet another embodiment of the present invention; and

FIG. 8 is a partial perspective view of the upper end of the embodiment of FIG. 7.

Turning now to the drawings, in which the same reference numerals indicate corresponding elements throughout the several views, FIG. 1 illustrates a test tube assembly constructed in accordance with the teachings of the present invention. First provided is an elongate hollow test tube 10 having an open upper 11 and a closed bottom end 12. A piston 13 slidably disposed within the test tube 10 moves in response to an operating handle 14. As illustrated herein, the operating handle 14 consists of an elongate shaft 17 extending upwardly from the piston 13 and terminating at its upper end with a circular member 18 adapted for manual manipulation. Radially spaced veins 19 extending between the piston 13 and the upper member 18 and slidable against the inner wall 20 of the test tube 10 maintain the piston 13 in transverse alignment across the test tube.

The sequential deposition of serum into the bottom of the test tube is illustrated in FIGS. 1-3. It is understood that the piston 13 is withdrawn from the test tube during the deposition of the liquid. A coating 21 is applied to the inner surface of the bottom of the test tube during the manufacture of the test tube which is specifically sized and shaped to be inserted into a radioactivity counter. Such test tubes constructed of a material compatible with the testing equipment are generally commercially available from the manufacturers of the testing equipment. The reagent, herein shown in exaggerated thickness 21 for purposes of illustration, has an affinity for Hepatitis-Associated Antigen.

A syringe device 22 is used to deliver 0.l milliliter, approximately two drops, of blood serum 23 to be tested to the bottom of the test tube where, being a liquid, it will seek its own level and display the familiar convex meniscus.

After the blood is delivered to the bottom of the test tube, as above described, the piston 13 is inserted downwardly into the test-tube 10 until it bears against the serum. Herein the piston 13 is spaced above the bottom 12 to form a cavity therebetween having a volume equal to the volume of the serum 23 and the serum is maintained in constant contact with the reagent coating 21. A resilient plunger 24 associated with the piston 13 sealingly engages the inner wall 20 of the test tube to prevent the escape or evaporation of the serum 23. Pressure relief means, herein shown as an elongaated aperture 27, extend through the piston and the plunger to permit the escape of air as the piston is inserted downwardly within the test tube 10. While various pressure relief means may be suitably employed, it has been determined in accordance with the preferred embodiment of the present invention that an aperture having a diameter. of approximately 0.015 inch will be sensitive to the viscosity coefficient differential between the serum and the air, thereby permitting the air to pass therethrough, yet restricting the flow of the blood regardless of the disposition of the test tube apparatus during handling and shipment. If it is deemed necessary, due to the method of handling during shipment, the frictional fit between the plunger 24 and the inner wall 20 of the test tube is not sufficient to retain the piston 13 against the serum sample, suitable precautions may be taken such as affixing a strip of tape over the circular member 18 and down along the sides of the test tube 10.

An alternately preferred embodiment of the present invention, in which the upper portion of the assembly is modified to maintain the spaced relationship be tween the piston 13 and the bottom of the test tube 12, is illustrated in FIGS. 5 and 6. Herein, a cylindrical flange 30 having an inside diameter corresponding to the outside diameter of the test tube depends downwardly from the upper circular member 18. An annular projection 31 integral with the internal diameter of the cylindrical member 30 engages the upper portion of the test tube 10. It is obvious that the annular projection 31 may frictionally engage the upper portion of the test tube 10 or reside in a mating annular groove provided in the upper portion of the test tube. A flange 32 having an aperture 33 therein extends upwardly from the circular member 18 to provide a convenient fingerpull for withdrawing the piston from within the test tube.

In the embodiment of the invention, as illustrated in FIGS. 7 and 8, a cap 40 is detachably securable to the upper end of the test tube 10. An annular indentation 41 within the cap 40 engages a correspondingly shaped circumferential ridge 42 carried by the test tube 10, when the cap is inserted downward over the tube. A modified operating handle comprises an upwardly extending shaft 17 terminating at the upper end with a tab 43 having an aperture 44 extending therethrough. The tap functions for manual rotation and translation of the piston and shaft, 13 and 17 respectively, as will be hereinafter described in detail.

A pair of diametrically opposed keys 45 are carried by the shaft at a spacing below the tab 43 approximately equal to the thickness of the cap 40. An axial bore 48 having slots 49 extending radially therefrom accommodates the passage of the shaft 17 and the keys 45 through the cap 40. In this embodiment, after the serum has been deposited in the bottom of the test tube, the piston 13 is inserted into the open end of the test tube whereafter the cap 40 is slid downwardly along the shaft 17 to engage the upper end of the tube 10 and engagement is effected between the annular inkll dent 41 and the circumferential ridge 42. The tab 43 is then used to urge the piston 13 downwardly within the test tube 10. Concurrently, the keys 45 are aligned with the slots 49 and inserted therethrough to a position below the cap 40. Rotation of the tab through positions the keys 45 under the cap 40 in the location indicated by the dashed lines 50 to effectively lock the piston into the desired spaced relationship with the bottom of the test tube.

Having fully described and dislosed the present invention and the preferred embodiment thereof in such clear and concise terms as to enable those skilled in the art to understand and practice the same, the invention claimed is:

l. A test-tube assembly specially adapted for transporting a small quantity of a liquid while maintaining said liquid in continuous contact with a reagent coated on the inner surface of the bottom of said test tube, said assembly comprising:

a. an elongate, hollow test tube, closed on the bottom end;

b. a quantity of said reagent disposed as a coating on the inner surface of the bottom of said test tube;

0. a piston member shaped and dimensioned to be slidably received downwardly in and transversely across said test tube, sealingly peripherally engaging the inner wall of said test tube;

(1. an operating handle member extending upwardly from said piston for inserting said piston member downwardly into said test tube to a point spaced above the bottom thereof at a distance to maintain said liquid in continuous contact with said reagent; and

e. means defining a pressure-relief aperture in said piston member, said aperture sized to be sensitive to the viscosity coefficient differential between said liquid and air whereby air may pass therethrough,

but no liquid under transporting conditions, 

1. A TEST-TUBE ASSEMBLY SPECIALLY ADAPTED FOR TRANSPORTING A SMALL QUANTITY OF A LIQUID WHILE MAINTAINING SAID LIQUID IN CONTINUOUS CONTACT WITH A REAGENT COATED ON THE INNER SURFACE OF THE BOTTOM OF SAID TEST TUBE, SAID ASSEMBLY COMPRISING: A. AN ELONGATE, HOLLOW TEST TUBE, CLOSED ON THE BOTTOM END; B. A QUANTITY OF SAID REAGENT DISPOSED AS A COATING ON THE INNER SURFACE OF THE BOTTOM OF SAID TEST TUBE; C. A PISTON MEMBER SHAPED AND DIMENSIONED TO BE SLIDABLY RECEIVED DOWNWARDLY IN AND TRANSVERSELY ACROSS SAID TEST TUBE, SEALINGLY PERIPHERALLY ENGAGING THE INNER WALL OF SAID TEST TUBE, D. AN OPERATING HANDLE MEMBER EXTENDING UPWARDLY FROM SAID PISTON FOR INSERTING SAID PISTON MEMBER DOWNWARDLY INTO SAID TEST TUBE TO A POINT SPACED ABOVE THE BOTTOM THEREOF AT A DISTANCE TO MAINTAIN SAID LIQUID IN CONTINUOUS CONTACT WITH SAID REAGENT; AND E. MEANS DEFINING A PRESSURE-RELIEF APARTURE IN SAID PISTON MEMBER, SAID APERTURE SIZED TO BE SENSITIVE TO THE VISCOSITY COEFFICIENT DIFFERENTIAL BETWEEN SAID LIQUID AND AIR WHEREBY AIR MAY PASS THERETHROUGH, BUT NO LIQUID UNDER TRANSPORTING CONDITIONS. 